Early fire alarm systems typically included a single alarm panel coupled by wiring within a structure to various smoke detectors, fire alarm pull switches and annunciators to cause an alarm to be sounded upon detection of a fire to effect evacuation of persons from that structure. However, there are limitations associated with the scalability of the use of a single alarm panel in such systems. For example, single alarm panel systems may limit the available distance to detectors, switches and annunciators. Moreover, single alarm panel systems create a single point of failure that may disable alarm panel functionality for the entire system. Thus, larger structures, requirements for more and different types of detectors in each structure, and a desire to communicate the detection of alarm conditions among multiple structures have each necessitated the use of sets of multiple alarm panels linked by an alarm network to enable coordinated operation.
In many places, alarm networks must meet various safety standards for reliability and redundancy to both minimize equipment failures and sufficiently localize the effects of such failures to maintain coordinated operation among multiple alarm panels. In answer to such requirements, alarm networks have typically been formed among multiple alarm panels, whether within a single structure or among multiple structures, in a ring topology with a token-passing protocol to coordinate communications. In other words, alarm networks have typically been made up of point-to-point network segments extending between pairs of alarm panels that become nodes on that network, thereby forming a ring of alarm panel nodes and point-to-point network segments. Such a ring topology provides a redundant path between any two alarm panels on that ring.
However, depending on the circumstances under which an installation of such a network is undertaken, especially where such a network is retrofitted to existing structure(s), there may be difficulty in routing the wiring of the network segments to form a ring due to obstacles and/or distances between alarm panel locations. As a result, in order to form a ring, the lengths of one or more of the segments may need to be so great that data transfer rates are limited to mere kilobits per second. Further, the use of a ring topology can result in a considerable amount of traffic around the ring being slowed down to the data transfer rate of the slowest point-to-point segment in a ring. In at least some situations, it is possible to overcome such obstacles by forming multiple ring topologies and coupling pairs of rings with ring-to-ring bridging devices.
Further, considerable technical skill is required on the part of installation personnel to effectively plan a ring topology alarm network, or to plan an alarm network made up of two or more ring topologies linked by one or more ring-to-ring bridging devices. The need for such technical skill becomes more acute where an existing alarm network is to be augmented with more alarm panels such that locations must be found within an existing ring topology to insert one or more new alarm panels and/or to insert a ring-to-ring bridge to allow the addition of a new ring topology to accommodate new alarm panels. Such augmentation may be necessitated by a change in safety regulations requiring additional sensors, annunciators, pull switches, etc. in an existing structure; renovations made to an existing structure; and/or the addition of a new structure to a campus in which the alarm panels of multiple structures are linked. The training of installation personnel to provide them with the requisite level of skill is expensive. Such difficulties are likely to be exacerbated over time as alarm panels incorporate more capabilities. It is with respect to these and other considerations that the present improvements have been needed.